1. Field of the Invention
The present invention relates to a sheet feeding apparatus provided with a sheet cassette including a sheet stacking portion and an image forming apparatus provided with the sheet feeding apparatus.
2. Description of the Related Art
Frequently an image forming apparatus such as a copying machine, a FAX, and an LBP includes a sheet feeding apparatus that supplies a medium such as a cut sheet used to form an image to an image forming portion. Generally the sheet feeding apparatus includes a lifting and lowering device. In the lifting and lowering device, a stacking plate is provided as the sheet stacking portion in a sheet cassette, and the stacking plate is lifted and controlled in a position in which the sheet can be fed.
Generally a fixing member that fixes the stacking plate at a lowermost position is provided before shipping in order to prevent a breakage of the stacking plate or the lifting and lowering device due to a vibration of the stacking plate during shipment or movement of the apparatus. There is a possibility that a user drives the lifting and lowering device by turning on the power of the apparatus without removing the fixing member, which may lead to the breakage of the apparatus.
For example, U.S. Pat. No. 8,041,285 proposes a configuration in which the fixing member, which fixes a sheet loading plate that is of the stacking plate, is deformed by a lifting operation of the stacking plate with the lifting and lowering device, thereby automatically releasing the fixing of the sheet loading plate. In the configuration described in U.S. Pat. No. 8,041,285, a deformation member included in a mobile body retaining mechanism vertically downwardly abuts on part of the sheet loading plate, which can reciprocally moves within a movement range from a feeding position to a lower limit position, in the lower limit position. The deformation member is deformed such that the abutment on the sheet loading plate is released by a driving force from a lifting and lowering motor that lifts the sheet loading plate. The deformation member retracts to a position, in which the deformation member does not vertically downwardly abut on the sheet loading plate, by action of the driving force. The deformation member is fixedly supported in the lower limit position by a screw included in the mobile body retaining mechanism, and the deformation member is located in the position in which the deformation member does not vertically downwardly abut on the sheet loading plate. Therefore, even if the user forgets to remove the fixing member that restricts the movement of the sheet loading plate, the mobile body can normally be moved while the breakage is prevented.
However, in the related art, it is necessary to deform the fixing member in order to unlock the sheet loading plate that is of the stacking plate, and therefore the larger driving force is required for the lifting and lowering device. Therefore, it is necessary to use a motor that generates a torque equal to or more than necessary to lift and lower the stacking plate, which results in a problem of a cost increase or enlargement of the apparatus. In the related art, because the sheet loading plate cannot be locked again using the fixing member after the sheet loading plate is unlocked, the user cannot easily reuse the fixing member when moving the apparatus because of a move.
A sheet feeding apparatus and an image forming apparatus according to the present invention have a configuration in which the user can easily reuse the member, such as the fixing member, which is used in the locking while the motor having excessive performance is not used as the motor that lifts and lowers the stacking plate.